MEGAKARYOCYTE, ERYTHROID AND GRANULOCYTE-MACROPHAGE COLONY FORMATION IN MYELODYSPLASTIC SYNDROMES

Bone marrow progenitor cell assays of three cell lineages, i.e., colon y-forming unit megakaryocytes (CFU-Meg), burst-forming unit erythrocyt es (BFU-E) and colony-forming unit granulocyte-macrophages (CFU-GM), w ere performed for 21 patients with myelodysplastic syndromes (MDS). Ma rkedly reduced or absent colony formation was found in 67% of the pati ents for CFU-Meg and all patients except 2 with refractory anemia (RA) for BFU-E. Abnormal CFU-GM colony formation was found in only 5 of 12 patients with RA and RA with ring sideroblasts, in contrast to all of the RA patients with excess of blasts and excess of blasts in transfo rmation. Defective colony formation of all three cell lineages was see n in 63% of the MDS patients. The colony number of CFU-Meg correlated significantly with the numbers of both BFU-E and CFU-GM. These finding s indicate that hematopoiesis in MDS patients is disturbed due to a qu alitative or quantitative defect at the multipotent stem cell level.